China has been singled out by economists and the US government as having an undervalued currency. An implication is that over the years as the currency exchange rates approach fair value then the economies with undervalued currencies will be larger with future exchange rates.

By PPP measures China, Russia and India should have a lot of currency appreciation over the next few years for China, Brazil and Russia and a bit longer for India. (India is at an earlier development stage and will take longer to get currency appreciation) Brazil will have a little less from PPP but with increasing oil production will have a boost from the strength in the value of commodities (Russia gets a similar boost from commodity prices).

China should have double its current economy when exchange rates are fair value. Russia's economy should be 60% larger. India's economy should be nearly triple and Brazil's economy should be 20-25% larger.